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Saturday, 31 October

JEE Main 2020 · MathsMultiple choiceSingle correctMediumCalculation

JEE Main 9 January 2020, Shift 2, Maths Q59

Question 59 of 75 in this shift, Maths question 9 of 25, Section A. NTA dropped this question from the final key; it is left out of every count on this site.

If x=2sin⁡θ−sin⁡2θx=2\sin\theta-\sin2\theta and y=2cos⁡θ−cos⁡2θy=2\cos\theta-\cos2\theta, θ∈[0,2π]\theta\in[0,2\pi], then d2ydx2\frac{d^2y}{dx^2} at θ=π\theta=\pi is :
  1. (1)−38-\frac{3}{8}
  2. (2)−34-\frac{3}{4}
  3. (3)34\frac{3}{4}
  4. (4)32\frac{3}{2}

Official answer

Dropped by NTA (marks given to all)

NTA final key (Jan 2020).

Chapter
Continuity and Differentiability
Topic
Chain Rule
Idea tested
Chain Rule in Parametric Differentiation

Same idea in other shifts

Asked 1× in all
  1. 28 Jul 2022, Shift 2 · Q68Let x(t)=22cos⁡tsin⁡2tx(t)=2\sqrt{2}\cos t\sqrt{\sin 2t} and y(t)=22sin⁡tsin⁡2t, t∈(0,π2)y(t)=2\sqrt{2}\sin t\sqrt{\sin 2t},\ t\in\left(0,\frac{\pi}{2}\right). Then…HardSingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.